Re: PCI passthrough resource remapping

["Ryan C. Underwood" <nemesis@icequake.net>]

> > I have a multifunction PCI device that I'd like to pass through to KVM.
> > In order to do that, I'm reading that the PCI memory region must be 4K-page
> > aligned and the PCI memory resources itself must also be exact multiples
> > of 4K pages.
> > 
> > I have added the following on my kernel command line:
> > reassign_resources reassigndev=08:09.0,08:09.1,08:09.2,08:09.3,08:09.4
> > 
> > But I don't know if it has any effect.  The resources are still not
> > sized in 4K pages.  Also, this seems to screw up the last device.
> 
> I submitted a patch to qemu-kvm recently that got rid of that limitation. Please try out if the current git head works for you.

This works around that particular limitation, but now it looks like I
have to have VT-D for this to work at all.  (It seems so hard to find
documentation about PCI passthrough, probably because things are
changing all the time.)

device: 08:09.0: driver="pci-assign" host="08:09.0"
device: 08:09.1: driver="pci-assign" host="08:09.1"
device: 08:09.2: driver="pci-assign" host="08:09.2"
device: 08:09.3: driver="pci-assign" host="08:09.3"
device: 08:09.4: driver="pci-assign" host="08:09.4"
PCI region 0 at address 0xf4400000 has size 0x800, which is not a multiple of 4K. You might experience some performance hit due to that.
No IOMMU found.  Unable to assign device "08:09.0"
Failed to deassign device "08:09.0" : Invalid argument
Error initializing device pci-assign

-- 
Ryan C. Underwood, <nemesis@icequake.net>